not sure where you got that info from, but its not right at all. I used to have a firehawk and i ran 3.42's, 3.73's, and 4.11's in it with a T56.
on the highway about 70mph
3.42's were about 1900
3.73's were near 2300
4.11's were around 2700
like limequat said, T56 with the 89+ 3.73...